If you are looking for a more generic solution I can think of making an Ajax call on every survey page, passinbg a certain user ID to a PHP script. That script then gets the according data from an external DB and passes back an array which is read by some JS to populate the according survey fields (there are variations of that approach).

i actually solved it with a native parsing of the url.
i found the field names corresponded to the email url i was trying to push... so in the end i didn't have to do anything fancy except change the url to match what we being outputted by our template email to match that which LS was expecting.